From 1d055261b4144dbf86b2658437015b15d4dd9bff Mon Sep 17 00:00:00 2001
From: Richard <q@1bpm.net>
Date: Sun, 4 Sep 2022 00:32:56 +0100
Subject: initial

---
 include/jsoncons_ext/jsonpath/json_location.hpp | 445 ++++++++++++++++++++++++
 1 file changed, 445 insertions(+)
 create mode 100644 include/jsoncons_ext/jsonpath/json_location.hpp

(limited to 'include/jsoncons_ext/jsonpath/json_location.hpp')

diff --git a/include/jsoncons_ext/jsonpath/json_location.hpp b/include/jsoncons_ext/jsonpath/json_location.hpp
new file mode 100644
index 0000000..9105608
--- /dev/null
+++ b/include/jsoncons_ext/jsonpath/json_location.hpp
@@ -0,0 +1,445 @@
+// Copyright 2021 Daniel Parker
+// Distributed under the Boost license, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// See https://github.com/danielaparker/jsoncons for latest version
+
+#ifndef JSONCONS_JSONPATH_JSON_LOCATION_HPP
+#define JSONCONS_JSONPATH_JSON_LOCATION_HPP
+
+#include <string>
+#include <vector>
+#include <functional>
+#include <algorithm> // std::reverse
+#include <jsoncons/config/jsoncons_config.hpp>
+#include <jsoncons/detail/write_number.hpp>
+#include <jsoncons_ext/jsonpath/jsonpath_error.hpp>
+#include <jsoncons/json_type.hpp>
+
+namespace jsoncons { 
+namespace jsonpath {
+
+    template <class CharT>
+    class json_location; 
+
+    enum class json_location_node_kind { root, index, name };
+
+    template <class CharT>
+    class json_location_node 
+    {
+        friend class json_location<CharT>;
+    public:
+        using char_type = CharT;
+        using string_type = std::basic_string<CharT>;
+    private:
+
+        const json_location_node* parent_;
+        json_location_node_kind node_kind_;
+        string_type name_;
+        std::size_t index_;
+    public:
+        json_location_node(char_type c)
+            : parent_(nullptr), node_kind_(json_location_node_kind::root), index_(0)
+        {
+            name_.push_back(c);
+        }
+
+        json_location_node(const json_location_node* parent, const string_type& name)
+            : parent_(parent), node_kind_(json_location_node_kind::name), name_(name), index_(0)
+        {
+        }
+
+        json_location_node(const json_location_node* parent, std::size_t index)
+            : parent_(parent), node_kind_(json_location_node_kind::index), index_(index)
+        {
+        }
+
+        const json_location_node* parent() const { return parent_;}
+
+        json_location_node_kind node_kind() const
+        {
+            return node_kind_;
+        }
+
+        const string_type& name() const
+        {
+            return name_;
+        }
+
+        std::size_t index() const 
+        {
+            return index_;
+        }
+
+        void swap(json_location_node& node)
+        {
+            std::swap(parent_, node.parent_);
+            std::swap(node_kind_, node.node_kind_);
+            std::swap(name_, node.name_);
+            std::swap(index_, node.index_);
+        }
+
+    private:
+
+        std::size_t node_hash() const
+        {
+            std::size_t h = node_kind_ == json_location_node_kind::index ? std::hash<std::size_t>{}(index_) : std::hash<string_type>{}(name_);
+
+            return h;
+        }
+
+        int compare_node(const json_location_node& other) const
+        {
+            int diff = 0;
+            if (node_kind_ != other.node_kind_)
+            {
+                diff = static_cast<int>(node_kind_) - static_cast<int>(other.node_kind_);
+            }
+            else
+            {
+                switch (node_kind_)
+                {
+                    case json_location_node_kind::root:
+                        diff = name_.compare(other.name_);
+                        break;
+                    case json_location_node_kind::index:
+                        diff = index_ < other.index_ ? -1 : index_ > other.index_ ? 1 : 0;
+                        break;
+                    case json_location_node_kind::name:
+                        diff = name_.compare(other.name_);
+                        break;
+                }
+            }
+            return diff;
+        }
+    };
+
+    namespace detail {
+
+        template <class Iterator>
+        class json_location_iterator
+        { 
+            Iterator it_; 
+
+        public:
+            using iterator_category = std::random_access_iterator_tag;
+
+            using value_type = typename std::remove_pointer<typename std::iterator_traits<Iterator>::value_type>::type;
+            using difference_type = typename std::iterator_traits<Iterator>::difference_type;
+            using pointer = const value_type*;
+            using reference = const value_type&;
+
+            json_location_iterator() : it_()
+            { 
+            }
+
+            explicit json_location_iterator(Iterator ptr) : it_(ptr)
+            {
+            }
+
+            json_location_iterator(const json_location_iterator&) = default;
+            json_location_iterator(json_location_iterator&&) = default;
+            json_location_iterator& operator=(const json_location_iterator&) = default;
+            json_location_iterator& operator=(json_location_iterator&&) = default;
+
+            template <class Iter,
+                      class=typename std::enable_if<!std::is_same<Iter,Iterator>::value && std::is_convertible<Iter,Iterator>::value>::type>
+            json_location_iterator(const json_location_iterator<Iter>& other)
+                : it_(other.it_)
+            {
+            }
+
+            operator Iterator() const
+            { 
+                return it_; 
+            }
+
+            reference operator*() const 
+            {
+                return *(*it_);
+            }
+
+            pointer operator->() const 
+            {
+                return (*it_);
+            }
+
+            json_location_iterator& operator++() 
+            {
+                ++it_;
+                return *this;
+            }
+
+            json_location_iterator operator++(int) 
+            {
+                json_location_iterator temp = *this;
+                ++*this;
+                return temp;
+            }
+
+            json_location_iterator& operator--() 
+            {
+                --it_;
+                return *this;
+            }
+
+            json_location_iterator operator--(int) 
+            {
+                json_location_iterator temp = *this;
+                --*this;
+                return temp;
+            }
+
+            json_location_iterator& operator+=(const difference_type offset) 
+            {
+                it_ += offset;
+                return *this;
+            }
+
+            json_location_iterator operator+(const difference_type offset) const 
+            {
+                json_location_iterator temp = *this;
+                return temp += offset;
+            }
+
+            json_location_iterator& operator-=(const difference_type offset) 
+            {
+                return *this += -offset;
+            }
+
+            json_location_iterator operator-(const difference_type offset) const 
+            {
+                json_location_iterator temp = *this;
+                return temp -= offset;
+            }
+
+            difference_type operator-(const json_location_iterator& rhs) const noexcept
+            {
+                return it_ - rhs.it_;
+            }
+
+            reference operator[](const difference_type offset) const noexcept
+            {
+                return *(*(*this + offset));
+            }
+
+            bool operator==(const json_location_iterator& rhs) const noexcept
+            {
+                return it_ == rhs.it_;
+            }
+
+            bool operator!=(const json_location_iterator& rhs) const noexcept
+            {
+                return !(*this == rhs);
+            }
+
+            bool operator<(const json_location_iterator& rhs) const noexcept
+            {
+                return it_ < rhs.it_;
+            }
+
+            bool operator>(const json_location_iterator& rhs) const noexcept
+            {
+                return rhs < *this;
+            }
+
+            bool operator<=(const json_location_iterator& rhs) const noexcept
+            {
+                return !(rhs < *this);
+            }
+
+            bool operator>=(const json_location_iterator& rhs) const noexcept
+            {
+                return !(*this < rhs);
+            }
+
+            inline 
+            friend json_location_iterator<Iterator> operator+(
+                difference_type offset, json_location_iterator<Iterator> next) 
+            {
+                return next += offset;
+            }
+        };
+
+    } // namespace detail
+
+    template <class CharT>
+    class json_location
+    {
+    public:
+        using char_type = CharT;
+        using string_type = std::basic_string<CharT>;
+        using json_location_node_type = json_location_node<CharT>;
+    private:
+        std::vector<const json_location_node_type*> nodes_;
+    public:
+        using iterator = typename detail::json_location_iterator<typename std::vector<const json_location_node_type*>::iterator>;
+        using const_iterator = typename detail::json_location_iterator<typename std::vector<const json_location_node_type*>::const_iterator>;
+
+        json_location(const json_location_node_type& node)
+        {
+            const json_location_node_type* p = std::addressof(node);
+            do
+            {
+                nodes_.push_back(p);
+                p = p->parent_;
+            }
+            while (p != nullptr);
+
+            std::reverse(nodes_.begin(), nodes_.end());
+        }
+
+        iterator begin()
+        {
+            return iterator(nodes_.begin());
+        }
+
+        iterator end()
+        {
+            return iterator(nodes_.end());
+        }
+
+        const_iterator begin() const
+        {
+            return const_iterator(nodes_.begin());
+        }
+
+        const_iterator end() const
+        {
+            return const_iterator(nodes_.end());
+        }
+
+        const json_location_node_type& last() const
+        {
+            return *nodes_.back();
+        }
+
+        string_type to_string() const
+        {
+            string_type buffer;
+
+            for (const auto& node : nodes_)
+            {
+                switch (node->node_kind())
+                {
+                    case json_location_node_kind::root:
+                        buffer.append(node->name());
+                        break;
+                    case json_location_node_kind::name:
+                        buffer.push_back('[');
+                        buffer.push_back('\'');
+                        for (auto c : node->name())
+                        {
+                            if (c == '\'')
+                            {
+                                buffer.push_back('\\');
+                                buffer.push_back('\'');
+                            }
+                            else
+                            {
+                                buffer.push_back(c);
+                            }
+                        }
+                        buffer.push_back('\'');
+                        buffer.push_back(']');
+                        break;
+                    case json_location_node_kind::index:
+                        buffer.push_back('[');
+                        jsoncons::detail::from_integer(node->index(), buffer);
+                        buffer.push_back(']');
+                        break;
+                }
+            }
+
+            return buffer;
+        }
+
+        int compare(const json_location& other) const
+        {
+            if (this == &other)
+            {
+               return 0;
+            }
+
+            auto it1 = nodes_.begin();
+            auto it2 = other.nodes_.begin();
+            while (it1 != nodes_.end() && it2 != other.nodes_.end())
+            {
+                int diff = (*it1)->compare_node(*(*it2));
+                if (diff != 0)
+                {
+                    return diff;
+                }
+                ++it1;
+                ++it2;
+            }
+            return (nodes_.size() < other.nodes_.size()) ? -1 : (nodes_.size() == other.nodes_.size()) ? 0 : 1;
+        }
+
+        std::size_t hash() const
+        {
+
+            auto it = nodes_.begin();
+            std::size_t hash = (*it).hash();
+            ++it;
+
+            while (it != nodes_.end())
+            {
+                hash += 17*(*it)->node_hash();
+                ++it;
+            }
+
+            return hash;
+        }
+
+        friend bool operator==(const json_location& lhs, const json_location& rhs) 
+        {
+            return lhs.compare(rhs) == 0;
+        }
+
+        friend bool operator!=(const json_location& lhs, const json_location& rhs)
+        {
+            return !(lhs == rhs);
+        }
+
+        friend bool operator<(const json_location& lhs, const json_location& rhs) 
+        {
+            return lhs.compare(rhs) < 0;
+        }
+    };
+
+    template <class Json>
+    Json* select(Json& root, const json_location<typename Json::char_type>& path)
+    {
+        Json* current = std::addressof(root);
+        for (const auto& json_location_node : path)
+        {
+            if (json_location_node.node_kind() == json_location_node_kind::index)
+            {
+                if (current->type() != json_type::array_value || json_location_node.index() >= current->size())
+                {
+                    return nullptr; 
+                }
+                current = std::addressof(current->at(json_location_node.index()));
+            }
+            else if (json_location_node.node_kind() == json_location_node_kind::name)
+            {
+                if (current->type() != json_type::object_value)
+                {
+                    return nullptr;
+                }
+                auto it = current->find(json_location_node.name());
+                if (it == current->object_range().end())
+                {
+                    return nullptr;
+                }
+                current = std::addressof(it->value());
+            }
+        }
+        return current;
+    }
+
+} // namespace jsonpath
+} // namespace jsoncons
+
+#endif
-- 
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